If you want to get strong and stay strong, then you’ve got to pump iron constantly. Push yourself to the max, then go even harder. That’s what Zhang Fuxing, a factor workers in Tangshan, Hebei province, China, does.

7 years ago, he made iron shoes weighing 440 pounds each. Every day, this 52-year old athlete walks 15 meters in them. Mr. Zhang says that the practice has cured his back pain and made him healthier:

“It’s not strong muscles that make you able to walk like this, the power comes from internal organs,” he said, adding: “When you walk with your heart it will work.”

Mr. Zhang plans to add 50 kilograms to his shoes. He leaves them outside his home. No one has ever stolen them.